Alternating-current plant combined with storage battery.



'L. SGHRCDBR & A. MI'TLLER.

ALTEBNATING CURRENT PLANT COMBINED WITH STORAGE BATTERY.

APPLICATION FILED OCT. 7,1904.

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Patented Mar. 21, 1911 lluiumlllllflllllllIIIJ UNITED STATES PATENTOFFICE.

LUDWIG soHRoDnR AND ADOLPH M JLLER, or BERLIN, GERMANY.

ALTERNATING-CURRENT PLANT COMBINED WITH STORAGE BATTERY.

T 0 all whom it may concern:

Be it known that we, LUDWIG Sonnonnn and AnoLrn Mtinnnn, subjects of theGerman Emperor, and residents of Berlin, Germany, have inventedImprovements in Alternating- Current Plants Combined with StorageBatteries.

Our invention relates to alternating current plant-s combined withstorage batteries and has the purpose to regulate the charging anddischarging of the storage battery in such a manner that if the currentused in the plant varies the main motor actuating the main generator isworking with constant load.

As is well known, electric plants, the currents of which are subjectedto great fluctuations, are combined with a storage battery being chargedby the excess of current not used in the plant and discharging currentinto the plant it there is more current wanted than generated by themain generator. In alternating current plants a rotary converter is tobe used, as the storage battery can only be charged by a direct orcontinuous current, the alternating current portion of this converterbeing connected with the wires of the plant and the direct currentportion being connected with the storage battery. It a small current isused in the plant the excess of current produced by the main generatorwill drive the rotary con1 verter and the current produced by the directcurrent portion will charge the battery. It on the contrary the plantuse more current than the main generator can produce then thealternating portion of the rotary converter will be driven by the directcurrent portion the battery discharging current into this portion andproducing alternating current assisting the current produced by the maingenerator. In this known system no special means were provided toregulate the charging and discharging current automatically, thisregulating being done by hand by regulating the shunt of the directcurrent portion of the transformer. The regulating of the charging anddischarging current was automatical only in the case, when by a strongdeclivity of the characteristics of the main generator the fluctuationsof intensity cause the tension of the alternating current to rise or tofall considerably.

Now our invention consists in regulating automatically the charging anddischarging current of the battery, even if there are no Specificationof Letters Patent.

Application filed October '7, 1904.

Patented Mar. 21, 1911.

Serial No. 227,527.

variations in the tension of the alternating current plant in such amanner that the main motor actuating the main generator is worltingalways with constant load.

We do not limit ourselves to the use of any particular kind ofalternating current apparatus, but preferably employ the socalledpolyphase system and arrange the wiring as shown in the accompanyingdrawing, in which the figure is diagrammatic and illustrates therelative arrangement of the various electric elements.

The main alternating current generator is shown at A and is driven by asteam engine, turbine, or analogous prime mover M, the main motor at Ebeing an alternating current motor, a motor generator consisting of thealternating current portion B and the direct current portion C coupledtogether, a storage battery at F, connected with the brushes of thedirect current portion by the wires '3 and S. A. transformer G isconnected by the wires 7, 8 with the alternating portion of a rotaryconverter D, the direct current portion of the latter being connected bywires 9 and 10 with a winding 2' upon the field of the direct currentportion. C of the motor generator B, C. Another winding h upon the fieldof the direct current portion C of this motor enerator opposes thewinding 2'. The leads 1, 2 and 3 connect the main generator A with themain motor E. The alternating current portion of the motor generator B,C, is connected by wires 4, 5 and 6 with the leads 1, 2 and 3.

The action of the system is as follows: If the current used in thealternating current motor E is very small the current flowing throughthe secondary winding of the transformer G, being also small, will beconverted by the rotary converter D into a small direct current flowingthrough the winding 2'. At the same time the motor generator B, C, isdriven by the excess current genererated by A. and not used by E, thedirect current generated by the portion C flows into the battery F, thehigh electromotive force of this current, necessary for charging thebattery, is produced by the field highly excited by the winding 7iproportional to the electro-motive force of the battery, and weakenedonly in a small degree by the small current flowing through the oppositewinding 2'. Therefore the battery F is charged with a large current anda high electro-motive force, if the amount of current used in E issmall. If an excess of current is wanted in the motor E, the directcurrent in the winding 2' is large, thereby greatly weakening themagnetic field and the electro-motive force of the portion C of themotor generator to such a degree that the electro-motive force of thebattery F is greater than that of the direct current portion C of themotor generator B, C. Therefore the battery is discharged into theportion C which acts as a motor and drives the portion B which nowgenerates alternating currents feeding the plant E together with themain generator A. In this manner the main generator constantly furnishesnearly the same intensity of current with the same tension or with smallfluctuations of tension independent of the amount of current used in theplant at different times, the charging and discharging of the batterybeing regulated automatically. and the prime mover M actuating the maingenerator A, being worked constantly at the same load.

ive find in general that arrangement is better adapted for branches fromthe main line than for trunl: lines though either of the systems abovedescribed may be used upon such trunk lines.

Having thus described our invention we claim as new and desire to secureby Letters Patent:

The combination of a main alternating current generator, alternatingcurrent mains fed thereby, a motor generator, both sides of which canact as motor as well as generator, and the direct current side of whichis provided with an armature and two field windings opposing each otherconductors from the alternating current side of said motor generator tosaid alternating current mains, a storage battery, connect-ions betweenthe armature of the direct current side of said motor generator and saidstorage battery, connections between one of the field windings of thedirect current side of said motor generator and said storage battery, aseries transformer the primary coil of which is inserted in one of saidalternating current mains, a rotary converter, connections between thealternating current side of said rotary converter and the secondary coilof said series transformer. and connections between the direct currentside of said rotary converter and the second field winding on the directcurrent side of the said 1110- 55 tor generator.

In testimony whereof we have signed our names to the specification. inthe presence of two subscribing witnesses.

LUDlVIG SQHRODER. ADOLPH MULLER. lVitnesses HENRY Hnsrnn,

Vonnnamn Hanr'r.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

